Simplify UninitializedValues.cpp by removing logic to handle the previous (imprecise) representation
of '&&' and '||' in the CFG. This is no longer needed, and greatly simplifies the code.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160494 91177308-0d34-0410-b5e6-96231b3b80d8